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Exchange 2010 Queue errors, inconsistantly stops sending emails.

hotline100
hotline100 used Ask the Experts™
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Hi

We are having a rather strange problem with our new exchange 2010 server.

at least once a week it seems to randomly stop sending out emails with a 421 4.2.1 and a 451 4.4.0 error.

These are email domains that we frequently send a recieve from without any issues.

we can still recieve emails, but any mails sent to an external address just stack up for a few hours with the about errors.  they will eventually send however.

We have tried recreating the send connectors, restarting the transport services as recomended but it seems to be happening more frequently.

Can anyone suggest more options?

its a MS Server 2008 and exchange 2010, new to this version so "idiot" guides would be great.

i have attached a screen shot of the error messages.

Thanks.
exchange-2010-queue-errors..jpg
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It sounds as if the issue is on the receiving end. If this is occurring on domains you frequently send to, try doing as this link suggest.

http://social.technet.microsoft.com/Forums/en-US/exchangesvrtransport/thread/19d5d818-71d2-4959-b7c4-27f653ffcbd8

Author

Commented:
I have cleared the DNS cache and that seems to have resolved the problem at the moment.

However i will keep this question open for a day or so and monitor the issue.

thanks
Top Expert 2010
Commented:
hotline

Try this

Run the domains by MxToolbox.
This is for domains which you are trying to send - and receiving this 421 4.2.1 and a 451 4.4.0 e

www.mxtoolbox.com
Enter the domain name -
then in the result - click on Blacklist Test and SMTP Diag for the first MX record.

I am afraid CincyITSolutions is right.

Author

Commented:
ok will have a go thanks.

i ran a test on www.testmyexchange.com and it came back all ok, with nothing black/block listed.
Top Expert 2010

Commented:
I think you mean this >>
http://www.testexchangeconnectivity.com/